The invention relates to an electrochemical cell for the deionization of aqueous solutions by ion exchange wherein on one side the aqueous solution is conducted through an ion exchanger in the cell and a brine flow is conducted through a brine space in the cell which is separated from the ion exchanger by a membrane.
For the deionization of aqueous solutions, particularly in the manufacture of high-purity water electrodialysis cells utilizing a mixed bed ion exchanger technique are in use today. They use an electrodialysis unit as shown in the European patent application 0 170 895 and are designed in such a way that channels are formed between the cathode and the anode which are separated from one another by cation and ion permeable membranes. The electrode chambers arranged at the two opposite sides of the cell form brine spaces through which a brine flow is conducted. Adjacent each of the brine spaces toward the center of the cell, there is a resin chamber filled with ion exchanger material comprising a mixed bed of anionic and cationic exchanger resin. The two resin chambers are separated from each other by a central brine chamber arranged in the middle of the electrodialysis unit (see also GIT Fachz, Lab. March 1994, p.190-198). Such an electrodialysis cell unit can be extended by disposing, between the electrode spaces forming the brine chamber, additional resin and brine channels or chambers in an alternating sequence.
However, such electrodialysis cells filled with mixed resins have the disadvantage that an electrochemical regeneration of the ion exchanger bed is certain only if water dissociates to form protons and hydroxyl ions.
It is the object of the present invention to provide an electrochemical cell which can be controlled directly by an electric field or an electric current applied thereto. It is a further object of this invention to provide various arrangements of electrolysis cells as single cells or combination units of several cells.